The performance of plasma-assisted etch processes is frequently critical to the success of a semiconductor processing workflow. However, optimizing the etch processes can be difficult and time-consuming, oftentimes involving process engineers manually tweaking etch process parameters in an ad hoc fashion in attempt to generate the desired target feature profile. There is currently simply no automated procedure of sufficient accuracy which may be relied upon by process engineers to determine the values of process parameters which will result in a given desired etch profile.
Some models attempt to simulate the physical chemical processes occurring on semiconductor substrate surfaces during etch processes. Examples include the etch profile models of M. Kushner and co-workers as well as the etch profile models of Cooperberg and co-workers. The former are described in Y. Zhang, “Low Temperature Plasma Etching Control through Ion Energy Angular Distribution and 3-Dimensional Profile Simulation,” Chapter 3, dissertation, University of Michigan (2015), and the latter in Cooperberg, Vahedi, and Gottscho, “Semiempirical profile simulation of aluminum etching in a Cl2/BCl3 plasma,” J. Vac. Sci. Technol. A 20(5), 1536 (2002), each of which is hereby incorporated by reference in its entirety for all purposes. Additional description of the etch profile models of M. Kushner and co-workers may be found in J. Vac. Sci. Technol. A 15(4), 1913 (1997), J. Vac. Sci. Technol. B 16(4), 2102 (1998), J. Vac. Sci. Technol. A 16(6), 3274 (1998), J. Vac. Sci. Technol. A 19(2), 524 (2001), J. Vac. Sci. Technol. A 22(4), 1242 (2004), J. Appl. Phys. 97, 023307 (2005), each of which is also hereby incorporated by reference in its entirety for all purposes. Despite the extensive work done to develop these models, they do not yet possess the desire degree of accuracy and reliability to find substantial use within the semiconductor processing industry.